And So It Begins

We are now a few hours into a long winter-storm period.  We picked up about 3-4" of heavy snow at my place overnight, but given the mild temps, the major roads were in good shape when I drove in early this morning.  Campus looks spectacular.  

The wet snow is sticking to everything.  It makes for beautiful scenes, but might lead to downed limbs and powerlines as this stacks up.  

In the mountains, overnight totals were greatest in the northern Wasatch.  Snowbasin is reporting 13" and PowMow 11".  

Snowfall rates at Alta-Collins picked up after 4 AM.  I can't tell if the interval board was wiped at 4 AM or not from these observations.  If it was, they are up to 7" as of 7 AM.  Otherwise it's 5" with 0.45" of water.  

As of 1329 UTC (0729 MDT) radar shows the frontal band parked right over the Salt Lake Valley, Utah Valley, and the central Wasatch, as the models have been advertising for a few days.

I didn't try to save a loop, but it shows strong confluence of the large-scale flow over the area too with southwesterly flow ahead of the front and westerly flow behind it.  That's a good recipe for what meteorologists call frontogenetical forcing, meaning the tendency for the flow to strengthen the front.  This often drives vertical circulations that yield just what you see above.  A broad band of frontal precipitation. 

For today, be it in the Salt Lake Valley or the central Wasatch, expect snow.  It will be a snow-globe day for valley dwellers.  Get into the holiday spirit.  Oh wait, that season was months ago.  

As an example of what the models are doing for today, below is our HRRR-derived snowfall guidance for the six-hour period ending at 0000 UTC 4 April (6 PM MDT Monday).  Basically, this is the HRRR guidance for this afternoon.  It's putting out about 1.6" at the airport, 2.9" at Cottonwood Heights, and 6.6" at Alta.  

The GFS is roughly similar.  

In the valley, snow depths will depend some on what surface you measure on.  For the period from 7 AM through 6 PM today, I'm expecting another 4-8" on cold surfaces along the east bench and 5-10" at Alta-Collins (note that the HRRR guidance above is only for this afternoon and doesn't include this morning's snowfall). 

This is the first part of a long-duration storm.  Pace yourselves and monitor forecasts.